1. Field of the Invention
The present invention relates to an apparatus for and a method of measuring an optical alignment of an optical fiber block, and more particularly to an apparatus for and a method of measuring optical alignment conditions of optical fibers mounted to a V-groove array in an optical fiber block connected to the input or output terminals of an optical waveguide device.
2. Description of the Prior Art
Generally, an increase in the number of input/output terminals in an optical waveguide device such as a 1xc3x97N splitter, wavelength division multiplexer/demultiplexer, or optical switch results in a difficulty in attaching an optical fiber block to the input or output terminals of the optical waveguide device. Of course, the space between adjacent ones of waveguides at the input or output terminals in such an optical waveguide device and the position of each waveguide on a substrate can have an accuracy of micron or less by virtue of an accurate photolithography. On the other hand, where optical fibers are attached to the input or output terminals of the optical waveguide device, it is required to arrange those optical fibers at desired positions, respectively. However, this process becomes more difficult as the number of the optical fibers used increases. To this end, it is necessary to use an optical fiber block in which optical fibers are accurately arranged in such a fashion that they are spaced apart from one another by a space corresponding to that of the optical waveguides at the input or output terminal of the optical waveguide device within an accuracy of micron or less.
However, such an optical fiber block has a structure fabricated by manually mounting single-core or multi-core optical fibers to a V-groove array. Due to such a structure, the optical fiber block may have a degraded reliability when it is attached to an optical waveguide device unless the alignment condition thereof is checked. In addition, there is a problem in that it is impossible to find an accurate alignment center of the optical fiber block. Therefore, it is necessary to provide an apparatus for and a method of measuring an optical alignment of the optical fiber block.
U.S. Pat. No. 5,703,973 for an Optical Integrated Circuit Having Passively Aligned Fibers And Method Using Same to Mettler et al discloses in FIG. 7 an apparatus for aligning optical fibers in an optical fiber array. Micropositioners are capable of finely positioning respective optical fiber arrays in three dimensions. A laser source is coupled to the ends of the optical fibers and can selectively generate laser light in any selected optical fiber. A light detector and a power meter generates a signal and intensity of laser light transmitted through the interconnection assembly. However, I have not seen a method for measuring the alignment of optical fibers in an optical fiber block that tests the first fiber on the edge of a block, the last fiber on the other edge of the block first before testing the optical fibers in between to achieve better measurement of alignment.
An object of the invention is to provide an apparatus for and a method of measuring an optical alignment of an optical fiber block, in which the optical alignment of the optical fiber block is measured by measuring the characteristics of the first and last ones of optical fibers mounted to a V-groove array in the optical fiber block, determining respective positions of those first and last optical fibers, and measuring the characteristics of the remaining optical fibers, based on the determined positions.
In accordance with one aspect, the present invention provides an apparatus for measuring optical alignment conditions of optical fibers mounted to an optical fiber block comprising: a light source; a measuring unit for measuring the characteristics of a light emitted from the light source and outputted from each of the optical fibers after passing through the optical fiber; and a control unit for determining respective central positions of the first and last ones of the optical fibers, based on the characteristics of the first and last optical fibers measured by the measuring unit, determining a direction connecting the determined central positions of the first and last optical fibers, and conducting a control for allowing the light emitted from the light source to be irradiated onto the remaining optical fibers in a sequential fashion along the determined direction, thereby allowing the measuring unit to measure the characteristics of the remaining optical fibers.
In accordance with another aspect, the present invention provides A method for measuring optical alignment conditions of optical fibers mounted to an optical fiber block comprising the steps of: irradiating a light emitted from a light source onto a first one of the optical fibers in the optical fiber block, and adjusting a central position of the first optical fiber in such a fashion that the light passing through the first optical fiber has a maximum power; irradiating the light emitted from a light source onto a last one of the optical fibers, and adjusting a central position of the last optical fiber in such a fashion that the light passing through the last optical fiber has a maximum power; and determining a direction connecting the adjusted central positions of the first and last optical fibers, and irradiating the light emitted from the light source onto the remaining optical fibers in the optical fiber block in a sequential fashion along the determined direction while measuring respective powers of lights outputted from the remaining optical fibers, thereby checking respective alignment conditions of the remaining optical fibers, and conducting a control for allowing the light emitted from the light source to be irradiated onto the remaining optical fibers, thereby allowing the measuring unit to measure the characteristics of the remaining optical fibers in the determined direction.
In accordance with another aspect, the present invention provides a method for measuring optical alignment conditions of optical fibers mounted to an optical fiber block comprising the steps of: irradiating a light emitted from a light source onto a first one of the optical fibers in the optical fiber block, and adjusting a central position of the first optical fiber in such a fashion that the light passing through the first optical fiber has a maximum power; irradiating the light emitted from a light source onto a last one of the optical fibers, and adjusting a central position of the last optical fiber in such a fashion that the light passing through the last optical fiber has a maximum power; and determining a direction connecting the adjusted central positions of the first and last optical fibers, and irradiating the light emitted from the light source onto the remaining optical fibers in the optical fiber block in a sequential fashion along the determined direction while measuring respective powers of lights outputted from the remaining optical fibers, thereby checking respective alignment conditions of the remaining optical fibers, and conducting a control for allowing the light emitted from the light source to be irradiated onto the remaining optical fibers, thereby allowing the measuring unit to measure the characteristics of the remaining optical fibers in the determined direction.